In communication systems, information traffic (“traffic”) is conventionally transported across shared media. Such traffic may be packet-based, cell-based, frame-based, or other type of information package. A scheduler controls access to such shared media. Thus, for example, packets may be queued in any of a variety of known queuing configurations, and the scheduler determines which queues may send packets and when they may be sent.
More recently, in over-the-air (“wireless”) networking, sharing of channels has become more problematic with an increase in wireless data traffic. This is becoming more problematic as more people use mobile products, such as portable smart phones, personal data assistants (“PDAs”), notebook computers, and the like to download information via the Internet. Concurrently, standards are emerging for this type of wireless communication. For example, with respect to packet downlink traffic, High-Speed Downlink Packet Access (“HSDPA”) is a packet-based data service for a Wideband Code Division Multiple Access (“W-CDMA”) downlink. HSDPA uses “fast scheduling” where the scheduler is moved from the Radio Network Controller (“RNC”) down to the Node-Bs, namely the base transceiver stations where W-CDMA is the air transport technology. Other examples of mobile protocols which include downlinking are CDMA2000, including Evolution-Data Optimized (“EV-DO”), and Worldwide Interoperability for Microwave Access (“WiMAX”). Notably, as used herein, “include” and “including” mean including without limitation.
Regardless of the protocol used, or at which node or station, including substation, the scheduler is located, it would be desirable and useful to provide increased channel reuse to accommodate situations where the number of channels is exceeded by the number of users attempting to access such channels. Notably, the term “user,” including plural forms thereof, is used interchangeably with the phrase “User Equipment (“UE”),” including plural forms thereof. Moreover, the term “node” as used herein is meant to include station, substation, and like types of points of presence in a network. The term “network” includes an air transport network, including a mesh network and a cellular network.
To increase channel reuse, a scheduler may take into account various factors depending on the protocol criteria implemented to determine the next queue to have packets sent from it. Examples of one or more factors that may be considered include packet length, queue fullness, the last queue to send, time since last packet sent from a queue, and available bandwidth on the downlink side, or any combination thereof. Additionally, the concept of “fairness” has been used in scheduling. Fairness basically means that each queue should be allotted its fair share of available bandwidth. A fair share may be an equal share subject to relative characteristics of the link, including UE capabilities.
Along those lines, others have proposed a “Proportional Fairness Scheduler” (“PFS”) to schedule access to channels. Generally a PFS will allocate more bandwidth to one or more users having the ability to receive higher data rates when such users' average usage rate has been lower. Weighting for allocation of bandwidth by a PFS is determined by the ratio of an instantaneous data rate to an average usage rate of each UE downlink. Instantaneous data rate in this context corresponds to quality of the link, namely the potential downlink data rate, and does not take into account actual data traffic usage of the link. Thus, a problem with a PFS is that high performance users, namely users capable of higher download speeds, generally are allocated excessive amounts of bandwidth during periods of relative inactivity of such high performance users or when such high performance users do not consume all of the bandwidth allocated to them, or a combination thereof. Allocation of too much bandwidth may have a significant impact on effectiveness of utilized bandwidth per user, which impact may become more apparent as link congestion increases.
Accordingly, it would be desirable and useful to provide a scheduler that provides enhanced channel reuse over that of a PFS.